Field of the Invention
The present invention relates to an adhesion detecting method for detecting the degree of adhesion of a protective tape attached to the front side of a wafer such as a semiconductor wafer.
Description of the Related Art
In a semiconductor device fabrication process, a plurality of crossing division lines are formed on the front side of a substantially disk-shaped semiconductor wafer to thereby define a plurality of separate regions, and a plurality of devices such as ICs and LSIs are each formed in these separate regions. The back side of the semiconductor wafer thus having the devices on the front side is ground to reduce the thickness of the semiconductor wafer to a predetermined thickness (back grinding step). Thereafter, the semiconductor wafer is cut along the division lines to thereby divide these separate regions where the devices are formed from each other, thus producing a plurality of individual device chips.
The back grinding step of grinding the back side of the semiconductor wafer to reduce the thickness of the semiconductor wafer to a predetermined thickness includes the steps of attaching a protective tape to the front side of the semiconductor wafer to protect the front side of the semiconductor wafer, next holding the semiconductor wafer on a chuck table of a grinding apparatus in the condition where the protective tape is in contact with the upper surface of the chuck table, and next grinding the back side of the semiconductor wafer by using abrasive members included in the grinding apparatus.
As a method of dividing a wafer such as a semiconductor wafer, there has been proposed a laser processing method including the steps of applying a pulsed laser beam having a transmission wavelength to the wafer from the back side of the wafer along each division line in the condition where the focal point of the pulsed laser beam is set inside the wafer, thereby continuously forming a modified layer inside the wafer along each division line, next grinding the back side of the wafer to reduce the thickness of the wafer to a predetermined thickness, and next applying an external force to the wafer to thereby break the wafer along each division line where the modified layer is formed to be reduced in strength, thus obtaining the individual device chips.
Also in this wafer dividing method, a protective tape is attached to the front side of the wafer, so as to protect the front side of the wafer (see Japanese Patent Laid-open No. 2009-290148, for example).